[llvm] [MCParser] Share identifier character set with isMacroArgChar (PR #219084)

[via llvm-commits]

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@@ -2459,13 +2459,12 @@ void AsmParser::DiagHandler(const SMDiagnostic &Diag, void *Context) {
     Parser->getContext().diagnose(NewDiag);
 }
 
-// FIXME: This is mostly duplicated from the function in AsmLexer.cpp. The
-// difference being that that function accepts '@' as part of identifiers and
-// we can't do that. AsmLexer.cpp should probably be changed to handle
-// '@' as a special case when needed.
-static bool isIdentifierChar(char c) {
-  return isalnum(static_cast<unsigned char>(c)) || c == '_' || c == '$' ||
-         c == '.';
+// A macro argument name ends at '@', '#' and '?', which may be identifier
+// characters.
+static bool isMacroArgChar(char C) {
+  return AsmLexer::isIdentifierChar(C, /*AllowAt=*/false,
+                                    /*AllowHash=*/false) &&
+         C != '?';
 }
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zhangweize9-cyber wrote:

That’s a great takeaway! My initial thought was just to rename the `isIdentifierChar` function.

https://github.com/llvm/llvm-project/pull/219084